Onan Genset

[glsponchos]

I have an onan genset on my 2010 allegro bus 43qrd. On the generator itself I have a single on off switch/breaker. I’ve always been under the assumption that the switch isolates the generator from the coach Is been doing some maintenance on the generator and was starting it several times. I turned the switch off thinking that it should prevent interruption to shore power. During my testing one of my air conditioners cycled. When I investigated, sure enough the coach was running off generator power. Appears throwing the switch has no impact on the generators operation. I called and asked Cummins. They said the switch must have failed in the closed position. Has anyone had this type of issue ? The genset is a QVD 10K

[twinboat]

Wow, is it a breaker and marked 35 or 40 amps ?

If it is, its actually a 2 pole breaker with one handle. Did everything work ?

[Tha_Rooster]

Post picture of your switch and breaker, that is strange. Mine has the start button and 2 breakers on genny.

[dennis45]

I'm confused. In your post I'm getting the impression you were plugged into shore power and running the generator. Yes, No?
Your transfer switch will always default to the generator.

[twinboat]

Originally Posted by dennis45

I'm confused. In your post I'm getting the impression you were plugged into shore power and running the generator. Yes, No?
Your transfer switch will always default to the generator.

The OP said the generator breaker is switched off. The transfer switch looks for generator output. No generator output, no transfer.

[Zigzag03]

In marine applications, which I am all to intimately familiar with, that breaker(s) 9kills any AC output to the system. But if you were plugged in as well, and the breaker was ON, or if it was OFF but had failed ON, should the transfer switch change over to generator in the presence of shore power? This I do not know. Boats don't typically have automatic transfer switches, it's done manually at the panel , although that may be changing, I've been off the front lines a couple years.

[ga traveler]

Was the motorhome plugged in when this happened? If it was, the loss of power from the generator would signal the changeover box to go back to shore power.

[glsponchos]

[glsponchos]

Yes the coach was plugged into shore power, but I had the breaker turned to the off position

[glsponchos]

Yes, everything appeared to work

[twinboat]

Originally Posted by glsponchos

Yes the coach was plugged into shore power, but I had the breaker turned to the off position

The shore power breaker ?

[Soppy]

That breaker should kill the generator output. If you are plugged into shore power , you will have AC power with that breaker in the off position.
The generator and shore power both go to a transfer switch , then to the coach. Generator power has priority , meaning with shore power connected and the generator producing power , the coach will be powered from the generator. If the breaker on the generator is turned off , the coach will get power from shore power.
To check if the breaker works , disconnect shore power , then start the generator with the breaker on . Once you have power to the coach , turn off the generator breaker . The coach should loose AC power.

[Zigzag03]

So as I read it he was plugged in, and had the genset breaker off, yet the transfer switch sensed generator input when he started and stopped it for service purposes, which I guess, but not sure, switched to the gen input regardless of shore power presence. So either he has a bad breaker, failed ON, or the gen is wired around the breaker, unlikely, or the transfer switch, having shore power present, should not be switching to gen, and that I don't know. Havn't owned mine a year yet, but she saved us in Irma. XO Big Mama

[glsponchos]

Originally Posted by twinboat

The shore power breaker ?

The gen set breaker in the photo